diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index 0cd33be7142ad0d8098e9c92832ff2230abc718c..0065209cc00424b3eda2ac7da96b2499e4852395 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -66,6 +66,7 @@ static inline void *dereference_symbol_descriptor(void *ptr)
}
#ifdef CONFIG_KALLSYMS
+unsigned long kallsyms_sym_address(int idx);
int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
unsigned long),
void *data);
diff --git a/init/Kconfig b/init/Kconfig
index abf65098f1b6bf1c70725a8d72de970a69efaced..c45935cd2f1f47119a85a25aa2a4a95ea2bedfe7 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1723,6 +1723,19 @@ config KALLSYMS
symbolic stack backtraces. This increases the size of the kernel
somewhat, as all symbols have to be loaded into the kernel image.
+config KALLSYMS_SELFTEST
+ bool "Test the basic functions and performance of kallsyms"
+ depends on KALLSYMS
+ default n
+ help
+ Test the basic functions and performance of some interfaces, such as
+ kallsyms_lookup_name. It also calculates the compression rate of the
+ kallsyms compression algorithm for the current symbol set.
+
+ Start self-test automatically after system startup. Suggest executing
+ "dmesg | grep kallsyms_selftest" to collect test results. "finish" is
+ displayed in the last line, indicating that the test is complete.
+
config KALLSYMS_ALL
bool "Include all symbols in kallsyms"
depends on DEBUG_KERNEL && KALLSYMS
diff --git a/kernel/Makefile b/kernel/Makefile
index d754e0be1176df3677c12fe2a9170acfef3a764a..e7fc37a6806979f07b63cf624829aa517d937c36 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -69,6 +69,7 @@ endif
obj-$(CONFIG_UID16) += uid16.o
obj-$(CONFIG_MODULE_SIG_FORMAT) += module_signature.o
obj-$(CONFIG_KALLSYMS) += kallsyms.o
+obj-$(CONFIG_KALLSYMS_SELFTEST) += kallsyms_selftest.o
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_CRASH_CORE) += crash_core.o
obj-$(CONFIG_KEXEC_CORE) += kexec_core.o
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 0008ada2b135bef30f98797cb89d703bce81fad0..83f499182c9aa319c2f56300754ac6fbfe1bc0b0 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -146,7 +146,7 @@ static unsigned int get_symbol_offset(unsigned long pos)
return name - kallsyms_names;
}
-static unsigned long kallsyms_sym_address(int idx)
+unsigned long kallsyms_sym_address(int idx)
{
if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
return kallsyms_addresses[idx];
diff --git a/kernel/kallsyms_selftest.c b/kernel/kallsyms_selftest.c
new file mode 100644
index 0000000000000000000000000000000000000000..c1d73ace63abb9807f4a8ff2556c33505c4e7987
--- /dev/null
+++ b/kernel/kallsyms_selftest.c
@@ -0,0 +1,485 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Test the function and performance of kallsyms
+ *
+ * Copyright (C) Huawei Technologies Co., Ltd., 2022
+ *
+ * Authors: Zhen Lei <thunder.leizhen@huawei.com> Huawei
+ */
+
+#define pr_fmt(fmt) "kallsyms_selftest: " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <linux/random.h>
+#include <linux/sched/clock.h>
+#include <linux/kthread.h>
+#include <linux/vmalloc.h>
+
+#include "kallsyms_internal.h"
+#include "kallsyms_selftest.h"
+
+
+#define MAX_NUM_OF_RECORDS 64
+
+struct test_stat {
+ int min;
+ int max;
+ int save_cnt;
+ int real_cnt;
+ int perf;
+ u64 sum;
+ char *name;
+ unsigned long addr;
+ unsigned long addrs[MAX_NUM_OF_RECORDS];
+};
+
+struct test_item {
+ char *name;
+ unsigned long addr;
+};
+
+#define ITEM_FUNC(s) \
+ { \
+ .name = #s, \
+ .addr = (unsigned long)s, \
+ }
+
+#define ITEM_DATA(s) \
+ { \
+ .name = #s, \
+ .addr = (unsigned long)&s, \
+ }
+
+
+static int kallsyms_test_var_bss_static;
+static int kallsyms_test_var_data_static = 1;
+int kallsyms_test_var_bss;
+int kallsyms_test_var_data = 1;
+
+static int kallsyms_test_func_static(void)
+{
+ kallsyms_test_var_bss_static++;
+ kallsyms_test_var_data_static++;
+
+ return 0;
+}
+
+int kallsyms_test_func(void)
+{
+ return kallsyms_test_func_static();
+}
+
+__weak int kallsyms_test_func_weak(void)
+{
+ kallsyms_test_var_bss++;
+ kallsyms_test_var_data++;
+ return 0;
+}
+
+static struct test_item test_items[] = {
+ ITEM_FUNC(kallsyms_test_func_static),
+ ITEM_FUNC(kallsyms_test_func),
+ ITEM_FUNC(kallsyms_test_func_weak),
+ ITEM_FUNC(vmalloc),
+ ITEM_FUNC(vfree),
+#ifdef CONFIG_KALLSYMS_ALL
+ ITEM_DATA(kallsyms_test_var_bss_static),
+ ITEM_DATA(kallsyms_test_var_data_static),
+ ITEM_DATA(kallsyms_test_var_bss),
+ ITEM_DATA(kallsyms_test_var_data),
+ ITEM_DATA(vmap_area_list),
+#endif
+};
+
+static char stub_name[KSYM_NAME_LEN];
+
+static int stat_symbol_len(void *data, const char *name, struct module *mod, unsigned long addr)
+{
+ *(u32 *)data += strlen(name);
+
+ return 0;
+}
+
+static void test_kallsyms_compression_ratio(void)
+{
+ u32 pos, off, len, num;
+ u32 ratio, total_size, total_len = 0;
+
+ kallsyms_on_each_symbol(stat_symbol_len, &total_len);
+
+ /*
+ * A symbol name cannot start with a number. This stub name helps us
+ * traverse the entire symbol table without finding a match. It's used
+ * for subsequent performance tests, and its length is the average
+ * length of all symbol names.
+ */
+ memset(stub_name, '4', sizeof(stub_name));
+ pos = total_len / kallsyms_num_syms;
+ stub_name[pos] = 0;
+
+ pos = 0;
+ num = 0;
+ off = 0;
+ while (pos < kallsyms_num_syms) {
+ len = kallsyms_names[off];
+ num++;
+ off++;
+ pos++;
+ if ((len & 0x80) != 0) {
+ len = (len & 0x7f) | (kallsyms_names[off] << 7);
+ num++;
+ off++;
+ }
+ off += len;
+ };
+
+ /*
+ * 1. The length fields is not counted
+ * 2. The memory occupied by array kallsyms_token_table[] and
+ * kallsyms_token_index[] needs to be counted.
+ */
+ total_size = off - num;
+ pos = kallsyms_token_index[0xff];
+ total_size += pos + strlen(&kallsyms_token_table[pos]) + 1;
+ total_size += 0x100 * sizeof(u16);
+
+ pr_info(" ---------------------------------------------------------\n");
+ pr_info("| nr_symbols | compressed size | original size | ratio(%%) |\n");
+ pr_info("|---------------------------------------------------------|\n");
+ ratio = (u32)div_u64(10000ULL * total_size, total_len);
+ pr_info("| %10d | %10d | %10d | %2d.%-2d |\n",
+ kallsyms_num_syms, total_size, total_len, ratio / 100, ratio % 100);
+ pr_info(" ---------------------------------------------------------\n");
+}
+
+static int lookup_name(void *data, const char *name, struct module *mod, unsigned long addr)
+{
+ u64 t0, t1, t;
+ unsigned long flags;
+ struct test_stat *stat = (struct test_stat *)data;
+
+ local_irq_save(flags);
+ t0 = sched_clock();
+ (void)kallsyms_lookup_name(name);
+ t1 = sched_clock();
+ local_irq_restore(flags);
+
+ t = t1 - t0;
+ if (t < stat->min)
+ stat->min = t;
+
+ if (t > stat->max)
+ stat->max = t;
+
+ stat->real_cnt++;
+ stat->sum += t;
+
+ return 0;
+}
+
+static void test_perf_kallsyms_lookup_name(void)
+{
+ struct test_stat stat;
+
+ memset(&stat, 0, sizeof(stat));
+ stat.min = INT_MAX;
+ kallsyms_on_each_symbol(lookup_name, &stat);
+ pr_info("kallsyms_lookup_name() looked up %d symbols\n", stat.real_cnt);
+ pr_info("The time spent on each symbol is (ns): min=%d, max=%d, avg=%lld\n",
+ stat.min, stat.max, div_u64(stat.sum, stat.real_cnt));
+}
+
+static bool match_cleanup_name(const char *s, const char *name)
+{
+ char *p;
+ int len;
+
+ if (!IS_ENABLED(CONFIG_LTO_CLANG))
+ return false;
+
+ p = strchr(s, '.');
+ if (!p)
+ return false;
+
+ len = strlen(name);
+ if (p - s != len)
+ return false;
+
+ return !strncmp(s, name, len);
+}
+
+static int find_symbol(void *data, const char *name, struct module *mod, unsigned long addr)
+{
+ struct test_stat *stat = (struct test_stat *)data;
+
+ if (strcmp(name, stat->name) == 0 ||
+ (!stat->perf && match_cleanup_name(name, stat->name))) {
+ stat->real_cnt++;
+ stat->addr = addr;
+
+ if (stat->save_cnt < MAX_NUM_OF_RECORDS) {
+ stat->addrs[stat->save_cnt] = addr;
+ stat->save_cnt++;
+ }
+
+ if (stat->real_cnt == stat->max)
+ return 1;
+ }
+
+ return 0;
+}
+
+static void test_perf_kallsyms_on_each_symbol(void)
+{
+ u64 t0, t1;
+ unsigned long flags;
+ struct test_stat stat;
+
+ memset(&stat, 0, sizeof(stat));
+ stat.max = INT_MAX;
+ stat.name = stub_name;
+ stat.perf = 1;
+ local_irq_save(flags);
+ t0 = sched_clock();
+ kallsyms_on_each_symbol(find_symbol, &stat);
+ t1 = sched_clock();
+ local_irq_restore(flags);
+ pr_info("kallsyms_on_each_symbol() traverse all: %lld ns\n", t1 - t0);
+}
+
+static int match_symbol(void *data, unsigned long addr)
+{
+ struct test_stat *stat = (struct test_stat *)data;
+
+ stat->real_cnt++;
+ stat->addr = addr;
+
+ if (stat->save_cnt < MAX_NUM_OF_RECORDS) {
+ stat->addrs[stat->save_cnt] = addr;
+ stat->save_cnt++;
+ }
+
+ if (stat->real_cnt == stat->max)
+ return 1;
+
+ return 0;
+}
+
+static void test_perf_kallsyms_on_each_match_symbol(void)
+{
+ u64 t0, t1;
+ unsigned long flags;
+ struct test_stat stat;
+
+ memset(&stat, 0, sizeof(stat));
+ stat.max = INT_MAX;
+ stat.name = stub_name;
+ local_irq_save(flags);
+ t0 = sched_clock();
+ kallsyms_on_each_match_symbol(match_symbol, stat.name, &stat);
+ t1 = sched_clock();
+ local_irq_restore(flags);
+ pr_info("kallsyms_on_each_match_symbol() traverse all: %lld ns\n", t1 - t0);
+}
+
+static int test_kallsyms_basic_function(void)
+{
+ int i, j, ret;
+ int next = 0, nr_failed = 0;
+ char *prefix;
+ unsigned short rand;
+ unsigned long addr, lookup_addr;
+ char namebuf[KSYM_NAME_LEN];
+ struct test_stat *stat, *stat2;
+
+ stat = kmalloc(sizeof(*stat) * 2, GFP_KERNEL);
+ if (!stat)
+ return -ENOMEM;
+ stat2 = stat + 1;
+
+ prefix = "kallsyms_lookup_name() for";
+ for (i = 0; i < ARRAY_SIZE(test_items); i++) {
+ addr = kallsyms_lookup_name(test_items[i].name);
+ if (addr != test_items[i].addr) {
+ nr_failed++;
+ pr_info("%s %s failed: addr=%lx, expect %lx\n",
+ prefix, test_items[i].name, addr, test_items[i].addr);
+ }
+ }
+
+ prefix = "kallsyms_on_each_symbol() for";
+ for (i = 0; i < ARRAY_SIZE(test_items); i++) {
+ memset(stat, 0, sizeof(*stat));
+ stat->max = INT_MAX;
+ stat->name = test_items[i].name;
+ kallsyms_on_each_symbol(find_symbol, stat);
+ if (stat->addr != test_items[i].addr || stat->real_cnt != 1) {
+ nr_failed++;
+ pr_info("%s %s failed: count=%d, addr=%lx, expect %lx\n",
+ prefix, test_items[i].name,
+ stat->real_cnt, stat->addr, test_items[i].addr);
+ }
+ }
+
+ prefix = "kallsyms_on_each_match_symbol() for";
+ for (i = 0; i < ARRAY_SIZE(test_items); i++) {
+ memset(stat, 0, sizeof(*stat));
+ stat->max = INT_MAX;
+ stat->name = test_items[i].name;
+ kallsyms_on_each_match_symbol(match_symbol, test_items[i].name, stat);
+ if (stat->addr != test_items[i].addr || stat->real_cnt != 1) {
+ nr_failed++;
+ pr_info("%s %s failed: count=%d, addr=%lx, expect %lx\n",
+ prefix, test_items[i].name,
+ stat->real_cnt, stat->addr, test_items[i].addr);
+ }
+ }
+
+ if (nr_failed) {
+ kfree(stat);
+ return -ESRCH;
+ }
+
+ for (i = 0; i < kallsyms_num_syms; i++) {
+ addr = kallsyms_sym_address(i);
+ if (!is_ksym_addr(addr))
+ continue;
+
+ ret = lookup_symbol_name(addr, namebuf);
+ if (unlikely(ret)) {
+ namebuf[0] = 0;
+ goto failed;
+ }
+
+ /*
+ * The first '.' may be the initial letter, in which case the
+ * entire symbol name will be truncated to an empty string in
+ * cleanup_symbol_name(). Do not test these symbols.
+ *
+ * For example:
+ * cat /proc/kallsyms | awk '{print $3}' | grep -E "^\." | head
+ * .E_read_words
+ * .E_leading_bytes
+ * .E_trailing_bytes
+ * .E_write_words
+ * .E_copy
+ * .str.292.llvm.12122243386960820698
+ * .str.24.llvm.12122243386960820698
+ * .str.29.llvm.12122243386960820698
+ * .str.75.llvm.12122243386960820698
+ * .str.99.llvm.12122243386960820698
+ */
+ if (IS_ENABLED(CONFIG_LTO_CLANG) && !namebuf[0])
+ continue;
+
+ lookup_addr = kallsyms_lookup_name(namebuf);
+
+ memset(stat, 0, sizeof(*stat));
+ stat->max = INT_MAX;
+ kallsyms_on_each_match_symbol(match_symbol, namebuf, stat);
+
+ /*
+ * kallsyms_on_each_symbol() is too slow, randomly select some
+ * symbols for test.
+ */
+ if (i >= next) {
+ memset(stat2, 0, sizeof(*stat2));
+ stat2->max = INT_MAX;
+ stat2->name = namebuf;
+ kallsyms_on_each_symbol(find_symbol, stat2);
+
+ /*
+ * kallsyms_on_each_symbol() and kallsyms_on_each_match_symbol()
+ * need to get the same traversal result.
+ */
+ if (stat->addr != stat2->addr ||
+ stat->real_cnt != stat2->real_cnt ||
+ memcmp(stat->addrs, stat2->addrs,
+ stat->save_cnt * sizeof(stat->addrs[0])))
+ goto failed;
+
+ /*
+ * The average of random increments is 128, that is, one of
+ * them is tested every 128 symbols.
+ */
+ get_random_bytes(&rand, sizeof(rand));
+ next = i + (rand & 0xff) + 1;
+ }
+
+ /* Need to be found at least once */
+ if (!stat->real_cnt)
+ goto failed;
+
+ /*
+ * kallsyms_lookup_name() returns the address of the first
+ * symbol found and cannot be NULL.
+ */
+ if (!lookup_addr || lookup_addr != stat->addrs[0])
+ goto failed;
+
+ /*
+ * If the addresses of all matching symbols are recorded, the
+ * target address needs to be exist.
+ */
+ if (stat->real_cnt <= MAX_NUM_OF_RECORDS) {
+ for (j = 0; j < stat->save_cnt; j++) {
+ if (stat->addrs[j] == addr)
+ break;
+ }
+
+ if (j == stat->save_cnt)
+ goto failed;
+ }
+ }
+
+ kfree(stat);
+
+ return 0;
+
+failed:
+ pr_info("Test for %dth symbol failed: (%s) addr=%lx", i, namebuf, addr);
+ kfree(stat);
+ return -ESRCH;
+}
+
+static int test_entry(void *p)
+{
+ int ret;
+
+ do {
+ schedule_timeout(5 * HZ);
+ } while (system_state != SYSTEM_RUNNING);
+
+ pr_info("start\n");
+ ret = test_kallsyms_basic_function();
+ if (ret) {
+ pr_info("abort\n");
+ return 0;
+ }
+
+ test_kallsyms_compression_ratio();
+ test_perf_kallsyms_lookup_name();
+ test_perf_kallsyms_on_each_symbol();
+ test_perf_kallsyms_on_each_match_symbol();
+ pr_info("finish\n");
+
+ return 0;
+}
+
+static int __init kallsyms_test_init(void)
+{
+ struct task_struct *t;
+
+ t = kthread_create(test_entry, NULL, "kallsyms_test");
+ if (IS_ERR(t)) {
+ pr_info("Create kallsyms selftest task failed\n");
+ return PTR_ERR(t);
+ }
+ kthread_bind(t, 0);
+ wake_up_process(t);
+
+ return 0;
+}
+late_initcall(kallsyms_test_init);
diff --git a/kernel/kallsyms_selftest.h b/kernel/kallsyms_selftest.h
new file mode 100644
index 0000000000000000000000000000000000000000..c0ca548e2a2259987fe93da3fcc28a602089e5cc
--- /dev/null
+++ b/kernel/kallsyms_selftest.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef LINUX_KALLSYMS_SELFTEST_H_
+#define LINUX_KALLSYMS_SELFTEST_H_
+
+#include <linux/types.h>
+
+extern int kallsyms_test_var_bss;
+extern int kallsyms_test_var_data;
+
+extern int kallsyms_test_func(void);
+extern int kallsyms_test_func_weak(void);
+
+#endif // LINUX_KALLSYMS_SELFTEST_H_